柠檬酸铝结构形态及其对部分水解聚丙烯酰胺-柠檬酸铝体系交联性质的影响

通过分析27Al核磁共振波谱、自旋晶格弛豫时间,结合数字拟合方法、渗析法和原子吸收分光光度法,对柠檬酸铝的形态结构及其影响因素进行了研究;利用转变压法研究了pH值对部分水解聚丙烯酰胺与柠檬酸铝体系交联过程的影响。结果表明,柠檬酸铝溶液中pH值增加时,Al(1)化学位移减少;pH值降低时,Al(2)化学位移减少。在柠檬酸铝溶液中存在两种形态的铝,一种是分子态,另一种是胶态。pH值增加时,分子态铝的量减少,而胶态铝的量增加。对部分水解聚丙烯酰胺与柠檬酸铝形成低聚合物浓度体系交联过程的研究表明,该反应所需柠檬酸铝为最佳形态结构时,溶液的pH值为5.0～7.0。

Effects of phase and structure of aluminum citrate solution on the crosslinking characteristics of hydrolytic polyacrylamide-aluminum citrate system

The phase of aluminum citrate in an aqueous solution was investigated by using ()~(27)Al nuclear magnetic resonance, spin-lattice relaxation time, digital matching, atomic absorption spectrography and dialysis methods. The influence of pH value on crosslinking characteristics of hydrolytic polyacrylamide-aluminum citrate (HPAM) system was studied by transition pressure method. The results show that the chemical shift of Al(1)in the aluminum citrate solution decreases with pH value increasing, and the chemical shift of Al(2) in the aluminum citrate solution decreases with pH value decreasing. There are two phases of aluminum in the aluminum citrate solution. One is in molecular state, and the other is in colloidal state. With the pH value of the solution increasing, the amount of aluminum in molecular state decreases and the amount of aluminum in colloidal state increases. The phase of aluminum citrate is available for crosslinking reaction of HPAM and aluminum citrate when the pH value of aluminum citrate solution ranges from 5.0 to 7.0.